I am confused as to how to include an externally defined subprocess in a process definition. I have created a process that I wish to reuse in a number of places. In order to invoke it from another process (call activity), I add a task (or collapsed subprocess), and modify the property attributes (e.g., 'Is a Call Activity'), but it doesn't seem to generate a callActivity element in the resulting BPMN XML. When I expand the subprocess (that I have tried to define as a call activity), the modeler opens a new tab of the same (parent) process, instead of the subprocess (call activity).
Can you please direct me to some documentation or help me understand how I should be incorporating reusable processes in other processes. Thank you.